Display system and vehicle

ABSTRACT

A display system and vehicle that have novel structures are provided. The display system includes a display panel, a correction circuit, and a memory circuit. The display panel is flexible. The display panel includes a display region and a non-display region. The memory circuit has a function of storing first data about the display region and second data about the non-display region. The non-display region has a region which overlaps with the display region when the display panel is bent. The correction circuit has a function of generating image data to be written to pixels in the display region on the basis of the first data and the second data.

This application is a continuation of copending U.S. application Ser.No. 16/705,657, filed on Dec. 6, 2019 which is a continuation of U.S.application Ser. No. 15/587,983, filed on May 5, 2017 (now U.S. Pat. No.10,504,489 issued Dec. 10, 2019) which are all incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

One embodiment of the present invention relates to a display system anda vehicle, and particularly relates to a display system including adisplay panel whose display surface is curved and a vehicle including aflexible display panel.

2. Description of the Related Art

A curved display including an organic electroluminescent (EL) elementhas been proposed (for example, in Patent Document 1). Note that thecurved display means a display including a curved display surface.

When the curved display is used for an instrument panel of a vehiclesuch as a car, the design improvement is expected (for example, inPatent Document 2).

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    2013-134295-   [Patent Document 2] Japanese Published Patent Application No.    2005-112251

SUMMARY OF THE INVENTION

In order to form a complex-shaped instrument panel using a curveddisplay, a plurality of display panels are combined. Display panelsusable in a complex-shaped instrument panel can improve not only thedesign but also the visibility or the like. However, in order to use aplurality of display panels having shapes different from each other,preparation of the differently shaped display panels is required. Forfabrication of a plurality of differently shaped display panels, thefabrication costs are increased.

An object of one embodiment of the present invention is to provide anovel display system and a vehicle or the like including the displaysystem.

Another object of one embodiment of the present invention is to providea novel display system which can suppress increase in the fabricationcosts even when display is performed with a combination use of aplurality of differently shaped display panels, and a vehicle or thelike including the display system. Another object of one embodiment ofthe present invention is to provide a novel display system capable ofimproving the visibility, and a vehicle or the like including thedisplay system.

One embodiment of the present invention is a display system including adisplay panel, a correction circuit, and a memory circuit. The displaypanel is flexible and includes a display region and a non-displayregion. The memory circuit has a function of storing first data aboutthe display region and second data about the non-display region. Thenon-display region has a region which overlaps with the display regionwhen the display panel is bent. The correction circuit has a function ofgenerating image data to be written to a pixel in the display region onthe basis of the first data and the second data.

One embodiment of the present invention is a display system including afirst display panel, a first correction circuit, a first memory circuit,a second display panel, a second correction circuit, and a second memorycircuit. The first display panel and the second display panel areflexible. The first display panel includes a first display region and afirst non-display region. The second display panel includes a seconddisplay region and a second non-display region. The first memory circuithas a function of storing first data about the first display region andsecond data about the first non-display region. The second memorycircuit has a function of storing third data about the second displayregion and fourth data about the second non-display region. The firstnon-display region has a region which overlaps with the first displayregion when the first display panel is bent. The second non-displayregion has a region which overlaps with the second display region whenthe second display panel is bent. The first correction circuit has afunction of generating first image data to be written to a pixel in thefirst display region on the basis of the first data and the second data.The second correction circuit has a function of generating second imagedata to be written to a pixel in the second display region on the basisof the third data and the fourth data.

In the display system of one embodiment of the present invention, thedisplay panel preferably includes a transistor and a display elementelectrically connected to the transistor, and the transistor preferablyincludes an oxide semiconductor in its channel formation region.

In the display system of one embodiment of the present invention, thedisplay element is preferably an organic electroluminescent element.

One embodiment of the present invention is a vehicle including aninstrument panel in which the above display system is used.

Note that other embodiments of the present invention will be shown inDETAILED DESCRIPTION OF THE INVENTION below and the drawings.

According to one embodiment of the present invention, a novel displaysystem and a vehicle or the like including the display system can beprovided.

According to another embodiment of the present invention, a noveldisplay system which can suppress increase in the fabrication costs evenwhen display is performed with a combination use of a plurality ofdifferently shaped display panels, and a vehicle or the like includingthe display system can be provided. According to another embodiment ofthe present invention, a novel display system capable of improving thevisibility, and a vehicle or the like including the display system canbe provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B illustrate a structure of display panels in a vehicle;

FIG. 2 illustrates a structure of display panels in a vehicle;

FIGS. 3A and 3B are a block diagram and a flow chart for explaining adisplay system;

FIG. 4 is a block diagram for explaining a display system;

FIGS. 5A to 5F are diagrams each explaining image data for displayingimages on a display panel;

FIGS. 6A and 6B each illustrate a structure example of a display panel;

FIGS. 7A to 7F each illustrate a structure example of a memory cell in amemory circuit;

FIGS. 8A and 8B illustrate a structure example of a pixel in a displaypanel;

FIG. 9 illustrates a structure of display panels in a vehicle;

FIG. 10 illustrates a structure of display panels in a vehicle;

FIGS. 11A and 11B illustrate a structure of display panels in a vehicle;

FIGS. 12A and 12B illustrate arrangement of imaging devices and displaypanels in a vehicle; and

FIGS. 13A to 13D show examples of vehicles.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings. Note that the embodiments of thepresent invention can be implemented with various modes, and it isreadily appreciated by those skilled in the art that modes and detailscan be changed in various ways without departing from the spirit andscope of the present invention. Thus, the present invention should notbe interpreted as being limited to the following description of theembodiments.

<Structure of Display System>

A structure example of a display system of one embodiment of the presentinvention will be described. This display system can be used for adisplay (also referred to as a display panel) having a curved displaysurface.

An example of a curved display surface is an instrument panel of avehicle such as a car. In the following examples of display systems,display systems are used in instrument panels of cars unless otherwisespecified. Note that the display system of one embodiment of the presentinvention can be used in not only in instrument panels of cars but alsoin displays as long as the displays have display surfaces. Examples ofvehicles other than cars include buses, trains, airplanes, and the like.

In FIG. 1A, an instrument panel of a vehicle and its vicinity areillustrated, and the instrument panel is provided with a display panelcapable of being used in a display system. In a vehicle 10, a pluralityof display panels 11A to 11D which are provided on a dashboard 12, asteering wheel 13, a window 14, and a pillar 15 are provided.

FIG. 1B is a cross-sectional schematic diagram of a display panel whichis capable of being used as the display panels 11A to 11D in FIG. 1A. InFIG. 1B, a display panel 20, which is any of the display panels 11A to11D, attached to the curved surface of the dashboard 12, in addition tothe dashboard 12 and the steering wheel 13, are illustrated. In thedisplay panel 20, a region whose surface is curved includes a displayregion 21, and the other regions include a non-display region 22 and acontrol IC 30.

A transistor, a display element, and the like of the display panel 20are provided over a flexible base. Thus, the display panel 20 isflexible. That is, the display panel 20 can be attached to the dashboard12 by being bent at bending portions 23 as illustrated in FIG. 1B. Thesebending portions 23 make the non-display region 22 and the displayregion 21 of the display panel 20 overlap with each other.

The control IC 30 has a function of generating image data. The controlIC 30 includes a memory circuit, a correction circuit, and the like, andgenerates image data to be written to pixels in the display region 21.

The memory circuit of the control IC 30 has a function of storingpositional data of pixels which form a display region and positionaldata of pixels which form a non-display region in the display panel 20.The display system of one embodiment of the present invention is formedusing a plurality of display panels. The plurality of display panelseach include their own display region and non-display region. Therefore,the control IC 30 in each of the display panels is provided with amemory circuit which is capable of storing positional data of pixelswhich form a display region and positional data of pixels which form anon-display region.

The correction circuit of the control IC 30 has a function of generatingimage data to be written in pixels which form a display region in thedisplay panel 20. That is, the correction circuit of the control IC 30corrects image data so as not to provide image data to pixels in thenon-display region and provide image data only to pixels in the displayregion. This makes it possible to rewrite image data only in pixelscontributing to display. Thus, unnecessary image data writing iseliminated, so that the power consumption can be reduced accordingly.

The control IC 30 in each of the display panels includes a correctioncircuit. This structure makes it possible for the display system of oneembodiment of the present invention to generate and output image datafor pixels in each of the display regions on the basis of informationabout pixels which form the display region, which differs between thedisplay panels.

FIG. 2 shows a specific example of the display system of one embodimentof the present invention. FIG. 2 illustrates the plurality of displaypanels 11A to 11D attached to the dashboard 12 in the vehicle 10 in FIG.1A. The display panels 11A to 11D in FIG. 2 have differently shapeddisplay surfaces. For example, the display panel 11B and the displaypanel 11C in FIG. 2 have differently shaped display surfaces.

A display surface having a complex shape like the display surfaces ofthe display panels 11A to 11D in FIG. 2 is formed using a combinationuse of a plurality of differently shaped display panels. The displaysystem of one embodiment of the present invention is effective informing such a structure. The display system of one embodiment of thepresent invention includes display panels each of which has its owndisplay region and whose non-display regions are bent. These displaypanels can be formed using the same display panels as base panelsbecause they can be formed to include their own display regions and canbe bent in their non-display regions. Therefore, the efficiency of massproduction can be increased. The use of a display panel used for thedisplay system of one embodiment of the present invention can reduce thefabrication costs.

Note that for the display panel in the display system of one embodimentof the present invention, a structure in which non-display regions of aplurality of display panels overlap with each other is also effective.In this case, a pixel included in a non-display region performs blackdisplay, so that the overlapping regions can be made inconspicuous. Inthe case of a rectangular display panel, it is difficult to bend all thefour sides. Therefore, a structure in which the non-display regionsperform black display and overlap with each other is effective inemploying a structure in which the non-display regions along two sidesof the rectangular display panel are bent and the non-display regionsalong the other two sides perform black display and overlap with eachother.

In the case of FIG. 2 , the display panel 11B and the display panel 11Ccan be formed using the same display panels. That is, the display panel11B and the display panel 11C can be formed from the display panels 20including same pixel portions 24 as illustrated in FIG. 2 . The displaypanels 20 serving as the display panel 11B and the display panel 11Cstore data in their memory circuits so that a display region 21D, adisplay region 21E, a non-display region 22D, and a non-display region22E are formed, and output different pieces of image data from theircorrection circuits on the basis of this data. The non-display regions22D and 22E not serving as display surfaces are provided so as to haveregions overlapping with the display regions when the display panels 20are bent, so that a space for attaching the display panel 20 can bereduced. In addition, a complex-shaped display surface like the displaysurfaces formed using the display panels 11A to 11D in FIG. 2 can beformed, and the display system whose design is improved can be achieved.

FIG. 3A is a block diagram for explaining a structure example of thecontrol IC 30. The control IC 30 in FIG. 3A includes, for example, aninterface 32, a correction circuit 33, a timing controller 34, a displaydriver IC 35, and a memory circuit 36. FIG. 3A also illustrates a hostcontroller 31 which applies image data to the control IC 30, the displaypanel 11 to which the control IC 30 applies corrected image data, anddisplay region data 37 as data stored in the memory circuit 36.

In the control IC 30, pre-corrected image data which is applied from thehost controller 31 is applied to the correction circuit 33 via theinterface 32. In the correction circuit 33, the pre-corrected image datais corrected to image data for the display region of the display panel11 with referring to the display region data 37 stored in the memorycircuit 36. The corrected image data is applied to the display panel 11via the timing controller 34 and the display driver IC 35.

FIG. 3B is a flow chart for explaining operation of the controller IC 30in FIG. 3A. Image data is input to the controller IC 30 (Step S01). Inthe correction circuit 33 of the controller IC 30, in order to correctimage data which is input and applied via the interface 32 to image datafor the display region, the display region data 37 stored in the memorycircuit 36 is read out and obtained (Step S02). The correction circuit33 corrects the original image data by performing arithmetic processingon the basis of the display region data 37 to image data for displayingan image in the display region (Step S03). The corrected image data isoutput to the display panel 11 via the timing controller 34 and thedisplay driver IC 35 (Step S04).

Note that the arithmetic processing performed in the correction circuit33 on the basis of the display region data 37 is image processing forprocessing original image data into image data which matches the shapeof the display region. For example, image processing is performed insuch a manner that original image data is partially removed so thatimage data to be applied to the pixels in the non-display region is madeblank. When image data which is applied to the pixels in the non-displayregion is converted into image data for black display, the powerconsumption can be reduced in a light-emitting display panel.Alternatively, arithmetic processing is performed in which the originalimage data is subjected to image processing so as to be compressed orenlarged and then converted into image data for the size of the displayregion.

The display region data can be mask data for each pixel in the displaypanel 11. Specifically, the mask data of a pixel in the display regionis “1” and the mask data of a pixel in the non-display region is “0” incoordinates of pixels. AND operations are performed for the mask dataand the image data to be subjected to the image processing incoordinates of pixels; thus, the image data of a pixel in thenon-display region can be set to “0,” to black display. In contrast, thevalue of the image data for a pixel in the display region is notchanged. This structure can freely fix the border between the displayregion and the non-display region.

As the other display region data, in the case of a rectangular displayregion, there are data of coordinates of vertexes of the rectangularregion and data to determine which of the upper, lower, left, and rightparts of straight lines connecting the data of vertexes becomes thenon-display region (non-display region determination data). With the useof the vertex coordinate data and the non-display region determinationdata, the image data can be determined to be inside or outside therectangular region, and the non-display data can be set to “0,” that is,to black display. Such a structure can reduce the amount of the datastored as the display region data.

Note that a block diagram of the display system in which a plurality ofdisplay panels are combined is shown in FIG. 4 . In FIG. 4 , the displaypanel 11A and the display panel 11B are illustrated as the plurality ofthe display panels. FIG. 4 also shows a controller IC 30A which appliesimage data to the display panel 11A and a controller IC 30B whichapplies image data to the display panel 11B. The host controller 31 canapply different image data to the controller IC 30A and the controllerIC 30B.

The controller IC 30A in FIG. 4 includes, for example, an interface 32A,a correction circuit 33A, a timing controller 34A, a display driver IC35A, and a memory circuit 36A. In FIG. 4 , display region data 37A isalso illustrated as data which the memory circuit 36A stores. Thecontroller IC 30B in FIG. 4 includes, for example, an interface 32B, acorrection circuit 33B, a timing controller 34B, a display driver IC35B, and a memory circuit 36B. In FIG. 4 , display region data 37B isalso illustrated as data which the memory circuit 36B stores.

When a display region of the display panel 11A is different from adisplay region of the display panel 11B in FIG. 4 , the display regiondata 37A in the memory circuit 36A is differentiated from the displayregion data 37B in the memory circuit 36B. In this structure, respectivepieces of image data matching the differently shaped display regions canbe output to the display panel 11A and the display panel 11B.

Note that a display region of the display panel which is provided on acurved surface is configured to display images as being curved. Forexample, schematic diagrams in FIGS. 5A and 5B illustrate the displaypanel 20A which displays images as being flat. FIG. 5A is a schematictop diagram and FIG. 5B is a schematic perspective diagram. In FIGS. 5Aand 5B, the pixel portion 24, a display region 21A, and a non-displayregion 22A are illustrated.

In FIG. 5C, the display panel 20A in FIG. 5B is illustrated as beingbent. As apparent from FIG. 5C, the display panel having a curvedsurface is differently visible depending on shapes of the curvedsurface, the user's viewpoint, or the like.

Thus, in the controller IC of the display panel, image data fordisplaying images on the display region may be changed depending on theshapes of the curved surfaces, or the like. Even in the case of therectangular display regions, the display region 21B is made to have acurved border as illustrated in the schematic diagrams of FIGS. 5D and5E, for example. Note that the pixel portion 24, a display region 21B,and a non-display region 22B are illustrated in FIGS. 5D and 5E.

In FIG. 5F, the display panel 20B in FIG. 5E is illustrated as beingbent. When the display region has a slightly fan-like shape like thedisplay region 21B illustrated in FIGS. 5D and 5E, the surface shape canbe seen to have less distortion when being bent. It is also possiblethat the image is seen three-dimensionally depending on the user'sviewpoint.

Note that the non-display regions 22A and 22B of the display panels 20Aand 20B in FIGS. 5A and 5D are regions which do not contribute todisplaying images. Therefore, as illustrated also in FIG. 1B, thenon-display region 22A and 22B are preferably bent. FIG. 6A shows aspecific example. In a display panel 20C in FIG. 6A, a display region21C and a non-display region 22C are provided. The display panel 20C canhave bending portions 23C by being bent near the borders between thedisplay region 21C and the non-display region 22C as illustrated in FIG.6A. The display panel 20C having the bending portions 23C can beprovided with a region where the display region 21C overlaps with thenon-display region 22C, and a space of the display panel can be reduced.

Note that a display panel which can be used in the display system of oneembodiment of the present invention can be provided in combination withanother component as appropriate. As an example, a display panel 20D inwhich the display panel 20 is combined with a polarizing plate 25 isillustrated in FIG. 6B. With the use of this structure, the direction(angle) in which the display panel is visible by the user can belimited; thus, the user can be more certain to see less distortedimages.

<Memory Cell Usable in Memory Circuit>

Structure examples of a memory cell usable in the above memory circuitwill be described with reference to FIGS. 7A to 7F.

FIG. 7A is a block diagram for explaining a structure example of thememory circuit. In the block diagram in FIG. 7A, a memory cell array 90,a word line driver circuit 91, and a bit line driver circuit 92 areillustrated.

In the memory cell array 90, memory cells MC are arranged in a matrix ofm rows and n columns (m and n are each a natural number). The memorycells MC are connected to word lines WL_1 to WL_m and bit lines BL_1 toBL_n. In addition to the bit lines and the word lines, the memory cellsMC may be connected to a source line for supplying current, a wiring forapplying voltage to a back gate of a transistor, a capacitor line forfixing a potential of one electrode of a capacitor element, or the like.

The word line driver circuit 91 is a circuit that outputs a signal forselecting memory cells MC in each row. Word lines for data writing andword lines for data reading may be provided separately as the word linesWL_1 to WL_m.

The bit line driver circuit 92 is a circuit for writing data into memorycells MC in each column, or for reading out data from the memory cellsMC in each column. Bit lines for data writing and bit lines for datareading may be provided separately as the bit lines BL_1 to BL_n.

FIGS. 7B to 7F each show an example of a circuit configuration that thememory cell MC illustrated in FIG. 7A can have.

A memory cell MC_A illustrated in FIG. 7B includes a transistor OS1 anda capacitor element 93. The transistor OS1 is a transistor containing anoxide semiconductor in its semiconductor layer (an OS transistor). TheOS transistor has a property of an extremely low leakage current in anon-conduction state (off-state current) as compared to a transistorcontaining silicon in its semiconductor layer (a Si transistor).Therefore, when the transistor OS1 is turned off, charge based on thedata can be stored in a charge retention node SN. Thus, the refresh rateof the data stored in the charge retention node SN can be reduced.

A memory cell MC B illustrated in FIG. 7C includes a transistor OS2 andthe capacitor element 93. The transistor OS2 is an OS transistor. Thetransistor OS2 differs from the transistor OS1 illustrated in FIG. 7B inthat a gate and a back gate are electrically connected to each other andvoltage of the word line WL is applied from both the gate and the backgate. Adopting such a structure can increase the amount of currentflowing between the source and the drain when the transistor OS2 isturned on.

A memory cell MC_C illustrated in FIG. 7D includes a transistor OS3 andthe capacitor element 93. The transistor OS3 is an OS transistor. Thetransistor OS3 differs from the transistor OS1 illustrated in FIG. 7B inthat a back gate and a back gate line BGL are electrically connected toeach other and voltage applied to the back gate is different fromvoltage applied to the gate. Adopting such a structure enables theamount of current flowing between the source and the drain to becontrolled by controlling the threshold voltage of the transistor OS3.

A memory cell MC_D illustrated in FIG. 7E includes the transistor OS1, atransistor M1, and the capacitor element 93. One of a source and a drainof the transistor OS1 is connected to a write bit line WBL. The other ofthe source and the drain of the transistor OS1 is connected to a gate ofthe transistor M1 and one electrode of the capacitor element 93. A gateof the transistor OS1 is connected to a write word line WWL. The otherelectrode of the capacitor element 93 is connected to a read word lineRWL. One of a source and a drain of the transistor M1 is connected to aread bit line RBL. The other of the source and the drain of thetransistor M1 is connected to a source line SL. Although the transistorM1 is a p-channel transistor in the diagram, the transistor M1 may be ann-channel transistor. When the transistor OS1 is turned off, chargebased on data can be stored in the charge retention node SN. Thetransistor M1 is a transistor containing silicon in its channelformation region (a Si transistor). Note that the transistor OS1 canhave the same structure as the transistor OS2 or OS3 described above.

A memory cell MC_E illustrated in FIG. 7F includes the transistor OS1,the transistor M1, a transistor M2, and the capacitor element 93. One ofthe source and the drain of the transistor OS1 is connected to the writebit line WBL. The other of the source and the drain of the transistorOS1 is connected to a gate of the transistor M1 and one electrode of thecapacitor element 93. A gate of the transistor OS1 is connected to thewrite word line WWL. The other electrode of the capacitor element 93 isconnected to a capacitor line CL. One of the source and the drain of thetransistor M1 is connected to one of a source and a drain of thetransistor M2. The other of the source and the drain of the transistorM1 is connected to the source line SL. A gate of the transistor M2 isconnected to the read word line RWL. The other of the source and thedrain of the transistor M2 is connected to the read bit line RBL.Although the transistor M2 is a p-channel transistor in the diagram, thetransistor M2 may be an n-channel transistor. When the transistor OS1 isturned off, charge based on data can be stored in the charge retentionnode SN. The transistor M2 is a Si transistor. Note that the transistorOS1 can have the same structure as the transistor OS2 or OS3 describedabove.

Note that the structures of the memory cells illustrated in FIGS. 7B to7F are effective especially when data to be stored in the memory circuitis increased. As compared to the structure where the memory cells in thememory circuit are constituted of static RAM (SRAM), the structure withone to three memory cells can inhibit an increase in a circuit area. Inparticular, the structures of the memory cells illustrated in FIGS. 7Bto 7D are effective in inhibiting an increase in a circuit area.

In addition, an OS transistor has transistor characteristics which areless likely to change when the operation temperature is increased than aSi transistor. Therefore, the memory circuit can be more certain tooperate in a temperature range for onboard use, such as in a car or thelike.

Note that the circuit configurations illustrated in FIGS. 7B to 7F aremerely examples, and any other configurations can be employed as long asone embodiment of the present invention can be achieved.

<Structure Example of Pixel in Display Panel>

In this section, a structure example of a pixel in a display panel whichcan be used in the above display system will be described.

FIG. 8A is a block diagram showing a structure example of the displaypanel.

A display panel 500 in FIG. 8A includes a driver circuit 541, a drivercircuit 542A, a driver circuit 542B, and a pixel portion 543. Note thatthe driver circuits 541, 542A, and 542B are collectively referred to asa driver circuit or a peripheral driver circuit in some cases.

The driver circuits 542A and 542B can function as, for example, scanline driver circuits. The driver circuit 541 can function as, forexample, a signal line driver circuit. Note that one of the drivercircuits 542A and 542B may be omitted. In addition, some sort of circuitfacing the driver circuit 541 with the pixel portion 543 providedtherebetween may be provided.

The display panel 500 illustrated as an example in FIG. 8A includes pwirings 544 that are arranged substantially parallel to each other andwhose potentials are controlled by the driver circuit 542A and/or thedriver circuit 542B, and q wirings 545 that are arranged substantiallyparallel to each other and whose potentials are controlled by the drivercircuit 541 (p and q are each a natural number of 1 or more). The pixelportion 543 includes a plurality of pixels 546 arranged in a matrix. Thepixel 546 includes a pixel circuit and a display element.

When every three pixels 546 function as one pixel, full-color displaycan be provided. Each of the three pixels 546 controls thetransmittance, reflectance, amount of emitted light, or the like foremitting red light, green light, or blue light. The light colorscontrolled by the three pixels 546 are not limited to the combination ofred, green, and blue, and may be yellow, cyan, and magenta.

A pixel 546 that controls white light may be added to the pixelscontrolling red light, green light, and blue light so that the fourpixels 546 will collectively function as one pixel. The addition of thepixel 546 that controls white light can heighten the luminance of thedisplay region. When the number of the pixels 546 functioning as onepixel is increased to use red, green, blue, yellow, cyan, and magenta inappropriate combination, the range of color reproduction can be widened.

A wiring 544_g in a g-th row (g is a natural number of more than orequal to 1 and less than or equal to p) is electrically connected to qpixels 546 in the g-th row among the plurality of pixels 546 arranged inp rows and q columns in the pixel portion 543. A wiring 545_h on theh-th column (his a natural number of more than or equal to 1 and lessthan or equal to q) is electrically connected to p pixels 546 on theh-th column among the plurality of pixels 546 arranged in p rows and qcolumns.

The display panel 500 can employ various modes and include variousdisplay elements. Examples of the display elements are elementsincluding a display medium whose luminance or the like is changed byelectric action, such as an electroluminescent (EL) element (e.g., anorganic EL element, an inorganic EL element, and an EL elementcontaining organic and inorganic materials) and the like.

A pixel 546A in FIG. 8B includes a transistor 461, a capacitor element463, a transistor 468, a transistor 464, and a light-emitting element426 capable of functioning as a display element.

One of a source electrode and a drain electrode of the transistor 461 iselectrically connected to the wiring 545_h. A gate electrode of thetransistor 461 is electrically connected to the wiring 544_g. The wiring545_h applies a video signal.

The transistor 461 has a function of controlling writing of a videosignal to a node 465.

One of a pair of electrodes of the capacitor element 463 is electricallyconnected to the node 465, and the other is electrically connected to anode 467. The other of the source electrode and the drain electrode ofthe transistor 461 is electrically connected to the node 465.

The capacitor element 463 functions as a storage capacitor for storingdata written to the node 465.

One of a source electrode and a drain electrode of the transistor 468 iselectrically connected to a potential supply line VL_a, and the other iselectrically connected to the node 467. A gate electrode of thetransistor 468 is electrically connected to the node 465.

One of a source electrode and a drain electrode of the transistor 464 iselectrically connected to a wiring VO, and the other is electricallyconnected to the node 467. A gate electrode of the transistor 464 iselectrically connected to the wiring 544_g.

One of an anode and a cathode of the light-emitting element 426 iselectrically connected to a potential supply line VL_b, and the other iselectrically connected to the node 467.

As the light-emitting element 426, an organic electroluminescent element(also referred to as an organic EL element) or the like can be used, forexample. Note that the light-emitting element 426 is not limitedthereto; an inorganic EL element including an inorganic material can beused, for example.

A high power supply potential VDD is applied to one of the potentialsupply line VL_a and the potential supply line VL_b, and a low powersupply potential VSS is applied to the other, for example.

In the display panel 500 including the pixel 546A in FIG. 8B, the pixels546 are sequentially selected row by row by the driver circuit 542Aand/or the driver circuit 542B, so that the transistor 461 is turned onand a video signal is written to the node 465.

The pixel 546A in which the data has been written to the node 465 isbrought into a holding state when the transistors 461 and 464 are turnedoff. The amount of current flowing between the source electrode and thedrain electrode of the transistor 468 is controlled on the basis of thepotential of the data written to the node 465. The light-emittingelement 426 emits light with a luminance determined by the amount offlowing current. This operation is sequentially performed row by row;thus, an image can be displayed.

The transistors 461, 464, and 468 may be transistors with back gates. Inthat case, in each of the transistors 461, 464, and 468, the gate may beelectrically connected to the back gate.

The above transistors 461, 464, and 468 are preferably OS transistors.As described above, the off-state current of OS transistors is extremelylow. Therefore, OS transistors can continue storing the potential ofdata written once to the node 465. When the same image is displayed, therefresh rate, a frequency of data writing, can be reduced; thus, thepower consumption can be reduced.

In addition, OS transistors can be formed at temperatures lower thanthat in the case of transistors in which their channel formation regionsare formed using low-temperature polysilicon (LTPS). Thus, the uppertemperature limit of the base for forming the OS transistors can belowered, which allows a range of selecting the materials to bebroadened. In particular, a several-μm-thick base can be selected as abase layer of a resin such as polyimide; therefore, the display panelcan be lighter and thinner. In addition, the display panel can be easilybent.

The organic EL element used as the light-emitting element 426 has apreferable response speed at low temperatures as compared to liquidcrystal elements. The display panels are used in a wide range of ambienttemperatures when being used for cars. Even in such a case, the displaypanel in which organic EL elements are used as the light-emittingelements can suppress reduction in the display quality.

In addition, the display panel in which organic EL elements are used asthe light-emitting elements has little change in the luminance due to adifference of the viewpoint positions as compared to a display panelusing liquid crystal elements. That is, the viewing angle dependence issmall. When the display panels are used for cars, information of themeter or the like can be correctly displayed without blur.

<Example of Using Display System for Vehicle>

A display panel capable of being used in the above display system isattachable to a surface so as to fit the shape of the surface.Hereinafter, examples in which the display panel is used for theperiphery of a driver's seat in a car, which is a vehicle, will bedescribed.

FIG. 9 illustrates a front glass and its vicinity inside a car, forexample. In FIG. 9 , display panels 51A to 51C which are attached to adashboard and a display panel 51D which is attached to a pillar areillustrated.

The display panels 51A to 51C can provide a variety of kinds ofinformation such as navigation data, a speedometer, a tachometer, amileage, a fuel meter, a gearshift indicator, and air-condition setting.The content, layout, or the like of the display on the display panelscan be changed freely to suit the user's preferences, so that the designcan be improved. The display panels 51A to 51C can also be used aslighting devices.

The display panel 51D can compensate for the view hindered by the pillar(blind areas) by displaying an image taken by an imaging unit providedfor the car body. That is, displaying an image taken by an imaging unitprovided on the outside of the car body leads to elimination of blindareas and enhancement of safety. In addition, showing an image so as tocompensate for the area which the driver cannot see makes it possiblefor the driver to confirm safety easily and comfortably. The displaypanel 51D can also be used as a lighting device.

FIG. 10 illustrates the inside of a car in which a bench seat is used asa driver seat and a front passenger seat. FIG. 10 illustrates a displaypanel 52A which is provided on a door, a display panel 52B which isprovided on a steering wheel, and a display panel 52C which is providedin the middle of the seating surface of the bench seat.

The display panel 52A can compensate for the view hindered by the doorby displaying an image taken by an imaging unit provided for the carbody, for example.

The display panels 52B and 52C can provide a variety of kinds ofinformation such as navigation data, a speedometer, a tachometer, amileage, a fuel meter, a gearshift indicator, and air-condition setting.The content, layout, or the like of the display on the display panelscan be changed freely to suit the user's preferences. The display panels52B and 52C can also be used as lighting devices.

The display panels provided everywhere inside the car as illustrated inFIG. 9 and FIG. 10 are effectively used as units for transmitting anurgent signal out of the car by being used as lighting devices. In thecase where an abnormal health condition of the user (driver) is sensedby a sensor or the like, for example, the display panels are made flashon and off at the highest luminance. The display panels in the displaysystem of one embodiment of the present can be provided everywhere inthe car and thus can transmit information effectively around the car ascompared to text information and a hazard lamp.

Like the above display panel, the display system of one embodiment ofthe present invention can be attached to a curved surface. Like theabove display panels 51A to 51D and display panels 52A to 52C, forexample, the display system can be attached everywhere inside the car.That is, the display system can be attached even to a curved surfacesuch as the dashboard 12 and the pillar 15 in FIG. 11A. Therefore, adisplay panel 60 can be provided on the inner surface of the car bodyexcept for windows 61 as illustrated in FIG. 11B. This structure candisplay images outside of the car body except for the outside of thewindows 61, so that blind areas can be eliminated and the safety can beenhanced.

When the display panels are provided on the inner surfaces of the carbody except for the windows 61 as illustrated in FIG. 11B, a pluralityof imaging devices 71L to 73L, and 71R to 73R are provided on the outerside of the car body as illustrated in FIG. 12A. Note that two or moreimaging devices are preferably arranged to obtain information about adistance to an object.

The structures in FIG. 11B and FIG. 12A make it possible to display theimages outside of the car body except for outside of the windows 61 asillustrated in FIG. 12B. Thus, the vehicle can compensate for the user'sblind areas and enhance its safety.

In the structure including the display panels 60 provided on the innersurfaces of the car body except for the windows 61, a position on whichthe meter or the like is displayed is changeable because the displaypanels are provided on a variety of places. In this case, the displaypositions can be switched freely to prevent the meter or the like frombeing difficult to see under direct sunlight.

<Examples of Vehicle>

Examples of a vehicle will be described.

The display system of one embodiment of the present invention can beused for a vehicle including a surface on which a display panel can beprovided. Specific examples of the vehicles are shown in FIGS. 13A to13D.

FIG. 13A illustrates a car 301. The car 301 includes a window 311. Avehicle of one embodiment of the present invention can be the car 301including the window 311. The display panel used for the display systemcan be provided on the surface inside the car 301. This structureenables the display panel in the car 301 to display outside images ofthe car 301. Thus, the car 301 can reduce the blind areas excluding thewindow 311.

FIG. 13B illustrates a bus 302. The bus 302 includes the window 311. Avehicle of one embodiment of the present invention can be the bus 302including the window 311. The display panel used for the display systemcan be provided on the surface inside the bus 302. This structureenables the display panel in the bus 302 to display outside images ofthe bus 302. Thus, the bus 302 can reduce the blind areas excluding thewindow 311.

FIG. 13C illustrates a train 303. The train 303 includes the window 311.A vehicle of one embodiment of the present invention can be the train303 including the window 311. The display panel used for the displaysystem can be provided on the surface inside the train 303. Thisstructure enables the display panel in the train 303 to display outsideimages of the train 303. Thus, the train 303 can reduce the blind areasexcluding the window 311.

FIG. 13D illustrates an airplane 304. The airplane 304 includes thewindow 311. A vehicle of one embodiment of the present invention can bethe airplane 304 including the window 311. The display panel used forthe display system can be provided on the surface inside the airplane304. This structure enables the display panel in the airplane 304 todisplay outside images of the airplane 304. Thus, the airplane 304 canreduce the blind areas excluding the window 311.

<Notes on Description of this Specification and the Like>

In this specification and the like, ordinal numbers such as “first,”“second,” and “third” are used in order to avoid confusion amongcomponents. Thus, the terms do not limit the number or order ofcomponents.

In a block diagram in this specification and the like, components arefunctionally classified and shown by blocks that are independent of eachother. However, in an actual circuit and the like, such components aresometimes hard to classify functionally, and there is a case in whichone circuit is concerned with a plurality of functions or a case inwhich a plurality of circuits are concerned with one function.Therefore, blocks in a block diagram do not necessarily show componentsdescribed in the specification, which can be explained with another termas appropriate depending on the situation.

The same elements or elements having similar functions, elements formedusing the same material, elements formed at the same time, or the likein the drawings are denoted by the same reference numerals, and thedescription thereof is not repeated in some cases.

In this specification or the like, the terms “one of a source and adrain” (or a first electrode or a first terminal) and “the other of thesource and the drain” (or a second electrode or a second terminal) areused to describe the connection relation of a transistor. This isbecause a source and a drain of a transistor are interchangeabledepending on the structure, operation conditions, or the like of thetransistor. Note that the source or the drain of the transistor can alsobe referred to as a source (or drain) terminal, a source (or drain)electrode, or the like as appropriate depending on the situation.

In this specification and the like, “voltage” and “potential” can bereplaced with each other. The term “voltage” refers to a potentialdifference from a reference potential. When the reference potential is aground potential, for example, “voltage” can be replaced with“potential.” The ground potential does not necessarily mean 0 V.Potentials are relative values, and the potential applied to a wiring orthe like is changed depending on the reference potential, in some cases.

In this specification and the like, a switch is conducting (on state) ornot conducting (off state) to determine whether current flowstherethrough or not. Alternatively, the switch is an element having afunction of selecting and changing a current path.

Examples of a switch are an electrical switch, a mechanical switch, andthe like. That is, any element can be used as a switch as long as it cancontrol current, without limitation to a certain element.

In the case of using a transistor as a switch, an “on state” of thetransistor refers to a state in which a source and a drain of thetransistor are electrically short-circuited. Furthermore, an “off state”of the transistor refers to a state in which the source and the drain ofthe transistor are electrically disconnected. In the case where atransistor operates just as a switch, the polarity (conductivity type)of the transistor is not particularly limited to a certain type.

In this specification and the like, when it is described that “A and Bare connected to each other,” the case where A and B are electricallyconnected to each other is included in addition to the case where A andB are directly connected to each other. Here, the expression “A and Bare electrically connected” means the case where electric signals can betransmitted and received between A and B when an object having anyelectric action exists between A and B.

This application is based on Japanese Patent Application serial No.2016-094469 filed with Japan Patent Office on May 10, 2016, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A display system comprising: a flexible display panel comprising: a display region; and a non-display region; and a control IC attached to the non-display region, the control IC comprising: a memory circuit configured to store display region data; a correction circuit configured to compress or enlarge first image data based on the display region data and convert the compressed or enlarged data into second image data for a size of the display region; and a display driver IC configured to output the second image data to the flexible display panel, wherein the display region has a curved surface, wherein the second image data is configured to have less distortion in the display region on the curved surface, wherein the flexible display panel comprises a bending portion near a border between the display region and the non-display region and is configured to be bent at the bending portion, and wherein when the flexible display panel is bent, the non-display region overlaps with the display region.
 2. The display system according to claim 1, wherein the display region displays an image as being flat.
 3. The display system according to claim 1, wherein the border between the display region and the non-display region is freely fixed.
 4. The display system according to claim 1, wherein the correction circuit is configured to generate third image data to be applied to the non-display region, and wherein the third image data is blank or black display.
 5. The display system according to claim 1, wherein the memory circuit comprises a memory cell, wherein the memory cell comprises: a first transistor whose semiconductor layer includes an oxide semiconductor; and a capacitor, one electrode of the capacitor electrically connected to one of a source and a drain of the first transistor.
 6. The display system according to claim 5, wherein the memory cell further comprises a second transistor whose semiconductor layer includes silicon, and wherein a gate of the second transistor is electrically connected to the one electrode of the capacitor and the one of the source and the drain of the first transistor.
 7. A display system comprising: a host controller; a first flexible display panel comprising: a first display region; and a first non-display region, a first control IC comprising: a first memory circuit configured to store first display region data; a first correction circuit configured to receive first image data from the host controller and compress or enlarge the first image data based on the first display region data and convert the enlarged or compressed data into second image data for a size of the first display region; and a first display driver IC configured to output the second image data to the first flexible display panel, a second flexible display panel comprising: a second display region; and a second non-display region, and a second control IC comprising: a second memory circuit configured to store second display region data; a second correction circuit configured to receive third image data from the host controller and process the third image data based on the second display region data to generate fourth image data to be written to the second display region; and a second display driver IC configured to output the fourth image data to the second flexible display panel, wherein the first display region and the second display region are different in size and shape, wherein the first flexible display panel comprises a bending portion near a border between the first display region and the first non-display region and is configured to be bent at the bending portion, and wherein when the first flexible display panel is bent, the first non-display region overlaps with the first display region.
 8. The display system according to claim 7, wherein at least one of the first display region and the second display region has a curved surface, and wherein the first display region and the second display region each display an image as being flat.
 9. The display system according to claim 7, wherein the shape of the first display region is rectangular, wherein the first flexible display panel is bent along two sides of the rectangular first display region, and wherein the other two side of the rectangular first display region overlaps with the second non-display region.
 10. The display system according to claim 7, wherein the first display region data and the second display region data are different from each other.
 11. The display system according to claim 7, wherein the first correction circuit is configured to generate fifth image data to be applied to the first non-display region, and wherein the fifth image data is blank or black display.
 12. The display system according to claim 7, wherein the first memory circuit comprises a memory cell, wherein the memory cell comprises: a first transistor whose semiconductor layer includes an oxide semiconductor; and a capacitor, one electrode of the capacitor electrically connected to one of a source and a drain of the first transistor.
 13. The display system according to claim 12, wherein the memory cell further comprises a second transistor whose semiconductor layer includes silicon, and wherein a gate of the second transistor is electrically connected to the one electrode of the capacitor and the one of the source and the drain of the first transistor. 